Grid whose cells are regularly spaced in a geographic (i.e., lat / long) or map
coordinate system defined in the Spatial Referencing System (SRS) so that any cell
in the grid can be geolocated given its grid coordinate and the grid origin, cell spacing,
and orientation indication of whether or not geographic.

Grid with cells irregularly spaced in any given geographic/map projection coordinate
system, whose individual cells can be geolocated using geolocation information
supplied with the data but cannot be geolocated from the grid properties alone.